1. Field of the Invention
This invention is directed to an unequivocal method of diagnosing cystic fibrosis, identifying carriers for cystic fibrosis, and non-carriers or "normal" persons.
Cystic fibrosis (CF) is an inherited disease of the exocrine glands, affecting most characteristically the pancreas, respiratory system, and sweat glands. It is transmitted within families as an autosomal recessive trait, affected individuals possessing a double dose of the mutant gene. Biological parents of subjects with CF each possess a single dose of the mutant gene and by definition are obligatory carriers for the condition. Carriers are, however, clinically normal and their detection prior to the birth of an affected child has been precluded by the absence of detectable effects of the gene in single dose. The disease has a 1:4 chance of occurring in a child of either sex if both parents are carriers. It primarily involves Caucasians and usually begins in infancy.
The disease is typified by chronic respiratory infection, pancreatic insufficiency, and susceptibility to heat prostrations. It is a major cause of death in children. It is estimated that there are between ten and twelve million carriers for cystic fibrosis in the United States. Eacy year between two and three thousand children are born in the United States who are affected by cystic fibrosis. The cost of therapy for cystic fibrosis patients is estimated at between about $15,000 to $20,000 per year per patient. Of patients diagnosed in early childhood, fewer than fifty percent reach adulthood.
2. The Prior Art
Prior to this invention, no carrier or prenatal detection procedure for cystic fibrosis existed. (Denning, C. R., et al: "Cystic Fibrosis: Projections into the Future", Mangos, J. A., Editors, Stratton Corporation, New York, pages 141-143, 1976) Diagnosis of the disease state was based on clinical signs and increased sweat salinity. No specific protein or enzyme assay for cystic fibrosis existed. (Nadler, H. L., et al: "The Metabolic Basis of Inherited Disease", Stanbury, J. B. et al, Editors, McGraw-Hill, New York, pages 1683-1710, 1978).